Access to effective breast cancer care is a critical factor in Appalachia contributing to health disparities among this population. Poor adherence to adjuvant cancer treatment has been reported to increase risk of death and associated with increased medical costs in breast cancer. Patient medication use behaviors are critical to the cancer heath disparities in Appalachia, and research on essential medication use and quality in rural areas is scant. Data suggests that designing an effective intervention targeting determinants of access to cancer care in Appalachia will provide patients an opportunity to receive appropriate medical treatment to alleviate disparity in cancer morbidity and mortality. The major impact of this study will be the production of a concrete intervention design aimed at reducing cancer health disparities in Appalachia by targeting modifiable contributors such as accessibility of medical care, quality and quantity of pharmacological treatment delivery, and adherence behaviors and their determinants. The purpose of this application includes an innovative approach to model accessibility to cancer care resource influences guiding appropriate treatment delivery and medication use behaviors (persistence and adherence to prescribed treatment), and how such factors impact cancer survival. Our central hypothesis is that patients who are able to access adequate medical care are more likely to receive standard treatments and persistently follow recommendations which lead to better therapeutic outcomes (such as survival). The strategies proposed will address the following specific aims: 1) Assess the complexity of the relationship between access to cancer care resources and patient prescribed guideline appropriate for adjuvant cancer treatments, 2) Delineate the manner in which specific social, system-specific, and individual determinants of access to cancer care affect patient medication use behaviors of persistence and adherence, and 3) Model cancer survival as a function of patient and system specific dimensions of access to cancer care, prescribing guideline appropriate adjuvant treatment and medication use behaviors. This study will use a unique NCI-funded linked dataset of 7,566 patients with breast cancer assembled from cancer registries, Medicare and Medicaid Services (CMS) Medicare claims data, US Social Security Administration's Death Master File (DMF), American Medical Association (AMA) Master file for information on physician and practitioners, American Hospital Dictionary (AHD) for healthcare facility characteristics. We hypothesize that there are modifiable individual and health-system related factors that impact the patient's receipt of optimal pharmacological treatment. The rationale for the proposed study is that, once medication access and utilization factors to which disparity in cancer survival can be attributed, are identified and accurately modeled, effective interventions targeting influential factors for breast cancer survival can be developed and tested in the same population and adapted to other populations burdened with similar inequalities, resulting in reducing health disparity in Appalachia and other regions.